Glass has been used as a material for an injection syringe. However, glass may be broken by dropping, and is being progressively replaced by plastics, such as polycarbonate, polyethylene, polypropylene, cyclic olefin polymer and the like.
Upon using an injection syringe, such a method has been practiced that a drug solution is suctioned into a vacant injection syringe upon using. However, the method has problems of poor operation efficiency and occurrence of human errors, such as malpractice on filling a drug solution and the like, and is progressively replaced by a prefilled syringe having a prescribed amount of a drug solution filled in advance.
Although a material for a prefilled syringe is preferably plastics because of the aforementioned factors, there is restriction in use due to water vapor permeability (moisture permeability), oxygen permeability and adsorbability, which are inherent to plastics, and thus it is the current situation that replacement to plastics does not proceed.
For example, an injection syringe made from polycarbonate has a problem in that water content of a drug vaporizes due to moisture permeability thereof, and an injection syringe made of polypropylene or cyclic olefin polymer has a problem in that a drug solution is oxidized due to oxygen permeability thereof, or a particular component of the drug is diluted due to adsorbability thereof.
It is known that a polyester resin is small in oxygen permeability and adsorbability. Polyethylene naphthalate also has low moisture permeability, but cannot use as a syringe since it suffers dimensional change through partial crystallization upon boiling sterilization due to crystallinity thereof. There is no known polyester resin that has both heat resistance withstanding boiling sterilization and low moisture permeability.
Patent Document 1 discloses a prefilled syringe made of a synthetic resin having low adsorbability with a gasket using butyl rubber, but it is not sufficient in high heat resistance, low adsorbability, low moisture permeability and low oxygen permeability.
[Patent Document 1] JP-A-2004-298220